Star Wars Aliens We Only Saw Once

The "Star Wars" universe is massive and filled with strange alien beings spread across a galaxy far, far, away. This multimedia franchise was the brainchild of George Lucas who started the phenomenon in 1977 with the very first "Star Wars" film. Since then, the series has exploded into nine main films, two spin-off movies, an animated film, and multiple television series, including "The Clone Wars" and "The Mandalorian". Suffice it to say, "Star Wars" isn't going anywhere anytime soon.

One of the features of "Star Wars" that makes it so interesting for fans is the level of creativity involved in making all the different species of aliens, even if they only appear for a moment. Unlike its main sci-fi competition, "Star Trek," the "Star Wars" universe isn't afraid to showcase aliens from other worlds that look truly different than the type of bipedal humanoids we're accustomed to. While most aliens in "Star Trek" are just humans painted a different color or given some face makeup, some species in "Star Wars" are genuinely bizarre to behold.

Certain "Star Wars" alien species show up repeatedly throughout the franchise, such as Yoda's unnamed species, which appears in both the original and prequel trilogy, as well as in "The Mandalorian" with the introduction of Grogu. However, most species are one-and-done. Part of the allure of this beloved space opera is that it will throw countless interesting science fiction concepts, stories, and alien races into the mix without always having the intention of bringing them back in any significant way. While almost every alien ever seen in the main films makes an appearance in the animated show at one point or another, this list will mainly focus on races only seen once in the main films, spin-offs, and Disney+ series.

When it comes to merciless warriors in the "Star Wars" universe, few are as fearsome as the Kaleesh. Coming from the hostile and primitive planet of Kalee in an area referred to as "wild space," the Kaleesh are an aggressive society of fighters who are ruled by regional warlords locked in frequent combat with little interaction with the galactic community. Because of this, there is only one notable Kaleesh in the entire "Star Wars" universe who is ever actually seen: General Grievous.

General Grievous is a major antagonist of the prequel films, shown to be the Supreme Martial Commander of the Separatist Droid Armies throughout the Clone Wars. Born under the name Qymaen jai Sheelal, he became immersed in the ongoing galactic conflict between the Republic and Separatist forces, joining the latter as a dedicated general. Unlike most Kaleesh, Grievous underwent extensive cybernetic modification which completely changed his appearance with a Kaleesh-inspired cyborg body to better help him fight against the Jedi. Interestingly, the character was intended to be foreshadowing of what Anakin Skywalker would become through his own cybernetic transformation into Darth Vader. George Lucas explains this in a behind-the-scenes featurette by saying, "he's an alien in a droid shell, which is sort of an echo of what Anakin would become." Ultimately, General Grievous is the only major Kaleesh seen in the entire "Star Wars" franchise, showing up in "Star Wars: Episode III – Revenge of the Sith" and as a frequent antagonist in "The Clone Wars."

The appropriately named Frog-dog species is an alien race that, you guessed it, looks like a hybrid of a frog and a dog. These strange-looking lizards are unique in the galaxy, being seemingly non-sentient when first encountered, despite the fact that they are very much aware of their surroundings. In fact, this seems to be a conscious effort to look inconspicuous and less intelligent than they actually are as a defense mechanism. This species was often kept as pets thanks to their docile nature, such as in the case of Buboicullaar.

This creature is shown to be a personal pet of Jabba the Hutt who resides in his palace on Tatooine. It's unknown what the homeworld of this species is, since it's never explicitly stated, but it is clear that Frog-dogs can acclimate to other environments, such as the hard desert world in which Buboicullaar lives. Frog-dogs are unable or unwilling to speak in the commonly used Galactic Basic language (aka, English) but instead bark like dogs, such as when Buboicullaar says "Arf! Arf!" to C-3P0 as he brushes past him. Buboicullaar is the only Frog-dog we see in the "Star Wars" universe during the Jabba's Palace scene in "Star Wars: Episode VI – Return of the Jedi."

Now here's a species that only hardcore "Star Wars" fans will remember: the Xexto. This six-limbed alien race comes from the distant Outer Rim world of Troiken, which fostered this unique species as an extremely adept organism. Xextos are mostly known for their talent at podracing, which is directly linked to the species' introduction into "Star Wars" canon with the Xexto podracer, Gasgano.

Gasgano is first shown in "Star Wars: Episode I – The Phantom Menace" as a male Xexto podracer on Tatooine alongside competitors like Sebulba and young Anakin Skywalker. Fans will recognize Gasgano during the thrilling Boonta Eve Podrace scene as piloting the green, dual-engine racer named "Ord Pedrovia," which survived the race by coming in second place. While there are some background Xexto audience members watching this race in the film, Gasgano remains the primary example of his species in the series, with no other Xexto showing up in later films or shows.

Exogorths are giant, monstrous space slugs that live inside asteroids throughout the galaxy. They are apparently a sentient species despite their behavior being rather feral in nature, trapping ships in their massive mouths by pretending to be an open cave entrance. Exogorths can grow to be absolutely colossal in size, with some being as large as 900 meters in length from head to tail. There is only one major Exogorth seen in the entire "Star Wars" franchise, and that's Sy-O. 

This space slug is encountered by the main cast of "Star Wars: Episode V – The Empire Strikes Back" as the Millennium Falcon unknowingly enters its mouth while attempting to hide from Imperial forces. Within the cave-like gullet of Sy-O, the ship is also attacked by native Mynocks, who live as parasites inside the Exogorth. These large worms were originally designed by artist Ralph McQuarrie as a piece of concept art which was later turned into the one on-screen Exogorth we see in the film, as seen in "The Art of Ralph McQuarrie".

Yet another species introduced during the podracing sequence in "Star Wars: Episode I – The Phantom Menace" is the Dug, a small but determined race of creatures from the planet Malastare in the Mid Rim Territories. The primary Dug encountered in the "Star Wars" universe is none other than Sebulba, a major antagonist of Anakin Skywalker in the first prequel film. The two are rival podracers who go head-to-head during the Boonta Eve Podrace, with Sebulba using trickery and sabotage to give himself as many advantages as possible. He's described succinctly by Anakin himself in "Star Wars: Episode I – The Phantom Menace," who says, "Your buddy here was about to be turned into orange goo. He picked a fight with a Dug, an especially dangerous Dug called Sebulba."

Designing the Dug was an interesting part of the production process for "Star Wars: Episode I – The Phantom Menace,” since George Lucas had a particular vision for the species. According to Terryl Whitlatch in "Star Wars: The Making of Episode I – The Phantom Menace," Lucas envisioned the way these creatures would walk and move ahead of time. He said, "George had the idea of a creature that walks on his hands and uses his feet as arms. Sebulba looks a bit like an arachnid, although his face is something like an arrogant camel. We definitely wanted him to look creepy." Sebulba is the only Dug seen in any of the major films or shows, aside from a small circus master character named Preigo in "The Clone Wars" series.

This feral, bloodthirsty species is one of the newer additions to the "Star Wars" canon, having been introduced in the first entry of J.J. Abrams' sequel trilogy in "Star Wars: Episode VII – The Force Awakens" as illegal cargo being smuggled by Han Solo. Rathtars are man-eating beasts from the toxic Outer Rim planet of Twon Ketee, where they are apex predators in their primitive world. Han Solo describes these animals best in the film when he simply says, "They are big and they are dangerous."

Rathtars were introduced into "Star Wars" as a scary (but not too scary) enemy for the main characters to face during Han Solo's re-introduction to the film. According to J.J. Abrams in the 3D Collector's Edition Blu-ray audio commentary for "The Force Awakens," Rathtars were meant to strike an interesting visual balance. He described them as "family-scary," meaning they were creepy enough to be exciting but not so horrifying that families and younger audiences would freak out seeing them. These creatures are only seen once in the "Star Wars" universe during their introduction, and never really heard from again.